Age 0-14 number of people= 206,423
Age 15-34 number of people= 265,778
Age 35-54 number of people= 308,946
Age 55-74 number of people= 159,092
Age over 74 number of people= 69,264
1)Classify the data in the table.
A)positively skewed
B)negatively skewed
C)normally distributed
D)discrete distribution
My first choice was C but I went with A instead.
2)For 2000 patients, a blood-clotting time was normally distributed with a mean of 8 seconds. What percent had blood-clotting times between 5 and 11 seconds?
A)68%
B)34%
C)49/5%
D)47/5%
I chose A
3)During a sale, 1/6 of the CD prices are reduced. Find the probability that 2 of 4 randomly-selected CDs have reduced prices?
A)5/36
B)25/1296
C)25/216
D)5/216
I don't know
4)A music teacher wants to determine the music performances of students. A survey of which group would produce a random sample?
A)students in the school band
B)students attendeing the annual jazz concert
C)students in every odd-numbered homeroom
D)every other player on the baseball roster
I chose B
5)In an election poll, 56% of 400 voters chose a certain canidate. Find the margin of sampling error.
A)5%
B)2%
C)4%
D)7%
I chose A
1) sounds fine.
2) How can you determine the percentages without knowing the Standard Deviation? You need a measure of variability.
3) The probability of picking a reduced DC is 1/6, not reduced = 5/6. The probability of picking 2 of each is 1/6 * 1/6 * 5/6 * 5/6 (multiply).
4) A random sample means that every student has an equal probability of being in the sample. Reconsider your answer.
5) Right.
I hope this helps. Thanks for asking.
I'm sorry #2 says For 2000 patients, a blood-clotting time was normally distributed with a mean of 8 seconds and a standard deviation of 3 seconds. What percent had blood-clotting times between 5 and 11 seconds?
Is #4 A?
1) To classify the data in the table, you can consider the shape of the distribution. In this case, the data represents the number of people in different age groups. To determine if the data is positively skewed, negatively skewed, normally distributed, or discrete, you can analyze the pattern.
In a positively skewed distribution, the majority of the data is on the left side and there are few extreme high values. In a negatively skewed distribution, the majority of the data is on the right side and there are few extreme low values. In a normally distributed dataset, the data is symmetrically distributed around a central value. In a discrete distribution, the data takes on specific fixed values.
Looking at the age group data, it appears to be discrete because it represents the count of individuals in different age groups, which are whole numbers. Therefore, the answer would be D) discrete distribution.
2) To find the percent of patients with blood clotting times between 5 and 11 seconds, you need to calculate the area under the normal distribution curve within that range.
Since the distribution is normal with a mean of 8 seconds, you can use the empirical rule, also known as the 68-95-99.7 rule, which states that approximately 68% of the data falls within one standard deviation of the mean in a normal distribution. Since the range from 5 to 11 seconds is two standard deviations away from the mean, the percentage would be approximately 68%.
Therefore, the correct answer would be A) 68%.
3) To find the probability that exactly 2 out of 4 randomly selected CDs have reduced prices, you can use combinatorics.
First, you need to determine the total number of possible outcomes, which is the number of ways to choose 2 CDs out of 4, which is denoted as C(4,2) or 4 choose 2. This can be calculated as 4! / (2! * (4-2)!) = 6.
Next, you need to find the number of favorable outcomes, which is the number of ways to choose 2 CDs with reduced prices out of the 4. Since 1/6 of the CDs have reduced prices, the probability of choosing a CD with a reduced price is 1/6. Therefore, the number of favorable outcomes is (1/6)^2 * (5/6)^2 = 25/1296.
Finally, you can calculate the probability by dividing the number of favorable outcomes by the total number of possible outcomes: 25/1296.
Therefore, the correct answer would be B) 25/1296.
4) To produce a random sample of music performances of students, you need to choose a representative group that is not biased towards any specific characteristic.
In this case, the best choice would be A) students in the school band, as this group would likely include students with different skill levels, interests, and backgrounds. Choosing students attending the annual jazz concert, students in every odd-numbered homeroom, or every other player on the baseball roster could introduce biases based on specific preferences, interests, or characteristics.
Therefore, the correct answer would be A) students in the school band.
5) To find the margin of sampling error, you need to consider the sample size and the confidence level.
In this case, the sample size is 400 voters, and 56% of them chose a certain candidate. Since this percentage is an estimate based on a sample, there will be some level of uncertainty.
The margin of sampling error is typically calculated using a formula: Margin of error = Z * (sqrt(p * (1-p)) / sqrt(n)), where Z is the z-score corresponding to the desired confidence level, p is the proportion of the population, and n is the sample size.
Assuming a confidence level of 95% (which corresponds to a Z-score around 1.96), the calculation can be done as follows: Margin of error = 1.96 * (sqrt(0.56 * (1-0.56)) / sqrt(400)).
Calculating this will give you the margin of sampling error, which is the maximum expected difference between the sample percentage and the true population percentage.
Based on the calculations, the correct answer would be B) 2%.
Note: It's important to note that these answers are based on the information and calculations provided. Double-checking calculations and assumptions is always encouraged for accurate results.